Core E will provide all histological, histochemical, electron microscopic and immunohistochemical techniques required by the four projects. In addition core E will provide histopathological interpretations and quantitative image analyses on tissues and cultured cells as required by the projects. Two pathologists and a histotechnician comprise the core personnel. The two pathologists work closely with the project directors to assure the quality of the experimental results. The core operates 5 microscopes equipped for fluorescence and bright field microscopy and digital imaging for use of the core personnel and researchers from the projects. The core also maintains two confocal microscopes for detailed fluorescence studies. The repertory of stains includes H&E, trichrome, methenamine silver and picric acid Sirius red. The most often employed immunostains are for Kit and Ki-67. In addition the core provides a wide range of immunohistochemical procedures using diverse antibodies. TUNEL assays for presumptive apoptotic cells are routine in the core. Quantitative image analytic procedures include cell frequency, collagen assay by direct a real measurement and point counting for volume density measurements on gross, light microscopic and electron microscopic images.